The research objectives of this program include (1) the evaluation of the mechanism of teratogenesis of kidney, placental and yolk sac antiserum in the rat. Determination of the cross specificity of the antigens in these tissues and the subcellullar source, number and types of antigens that can produce teratogenic antibodies; (2) the determination of the pathological events that follow the localization of antibodies on developing yolk sac that can result in abnormal embryonic development. These would include changes in yolk sac development, structure and permeability; (3) the evaluation of the role of yolk sac functions in species with less well-developed yolk sacs. It would be important to know whether yolk sac dysfunction can interfere with primate development and whether the antigenic relationships between rat kidney, placenta and yolk sac will exist in the primate; and (4) the evaluation of the mechanism of the protective effect of combining placental and kidney antisera; and trypan blue plus kidney antisera. The evaluation of the comparative teratogenicity of IgG and IgM teratogenic antibodies on a mole-for-mole basis; of fragments of teratogenic antibody upon nephrotoxicity, teratogenesis and abortion.